As shown in FIG. 1, a golf bag 31 is formed as a tall structure for accommodating golf clubs, and the weight of the accommodated golf clubs is concentrated at the upper portion of the golf bag. When a golf bag with such a structure is set upright on the ground, it is apt to fall over.
To increase stability, it is considered effective to increase the size of the base. The base diameter for a large size golf bag is as wide as 10 inches.
A general golf bag is equipped with a grip 32 for carrying the golf bag. Since golf clubs accommodated in the golf bag are composed of a shaft and a head having the center of gravity at a position offset from the shaft axial line, the heads are aligned in a specific direction, projecting in a direction opposite from the grip after carrying it, and the position of these clubs can exert a force that causes the golf bag to fall down.
Furthermore, golf bags typically are furnished with a front pocket 34 at the grip side and a back pouch 33 at the opposite side. When these pockets are filled, especially when the back pouch is filled with articles, the golf bag becomes even more likely to fall in the opposite direction from the grip.
Japanese Laid-open Utility Model No. 62-72672 discloses protrusions 38 formed near the base 37 on the grip side of the golf bag as shown in FIGS. 3-5, but this approach has been found not to be fully satisfactory.
There also exist bases formed in an elliptical shape having the major elliptical axis aligned with the grip and the opposite side (hereinafter called a front-rear direction as shown in FIG. 2), or a base in a square shape with smooth curved sides and round corners. Japanese Laid-open Utility Model No. 5-76470 also proposes a rectangular base.
When a base is larger, however, the mass of the base also increases. Although the center of gravity of the golf bag goes down with the increase of the base mass and the stability is improved, the golf bag itself becomes heavier, thus making it hard to handle. It also becomes hard to handle when a base is formed in a polygonal shape. When the inside diameter of a golf bag base is increased, golf clubs in the bag rest against a top frame 35 of the golf bag on one side with the grip ends of the clubs touching against the inner bottom of the other side of the golf bag. This increases the inclination of the golf clubs and also increases the force tending to cause the golf bag to fall over.
In summary, golf bags fall over after going through the following steps.
a. When the golf bag is set up on the ground, golf clubs accommodated in the golf bag incline toward the rear of the bag, opposite the grip.
b. Due to the inclination of the golf clubs, the golf bag also inclines in the same front-rear direction as the inclination of the golf clubs.
c. As a result of the inclination of the golf bag, the golf bag rotates along the base peripheral edge, shifting its direction of inclination from the front-rear direction to the lateral direction.
d. Due to the inclination of the golf bag in the lateral direction, the golf club heads move toward in the lateral direction, toward the side of the bag resulting in the inclination of the golf clubs in the lateral direction.
e. Due to the lateral inclination of the golf clubs, the lateral inclination of the golf bag increases further.
Because partitions at the top of the bag run side to side, as shown in FIG. 2, which illustrates such partitions 36, the golf bag becomes unstable dynamically like a shift of cargo when rotation of the golf bags begins at step c because the clubs readily shift to one side.
Because of this, although the arrangement of protrusions as shown in FIG. 3 or FIG. 4 proposed in Japanese Laid-open Utility Model No. 62-72672 is less likely to make the golf bag fall in the front direction, the forward inclination is followed by rotation, which instead promotes inclination of the clubs in the lateral direction and makes the golf bag more likely to fall over. The same thing happens with an elliptical base having the major axis in the front-rear direction or a square base with curved sides and round corners. When the protrusions are disposed as shown in FIG. 5, the bag becomes unlikely to fall in the front direction, but since there is no structure to improve the stability in the lateral direction toward which the bag is likely to fall, and since there is no rotation-preventing structure, falling is not adequately prevented.
The rectangular base disclosed in Japanese Laid-open Utility Model No. 5-76470 is designed such that the inclination in the front-rear direction is not transferred to the lateral direction. While it can be expected to have a preventive effect of rotation of a golf bag, the structure is narrow in the lateral direction in order to save space, and therefore, stability in the lateral direction is not necessarily improved.